Pin-straight, permanently smooth, or temporary?
Japanese straightening vs keratin treatment
Japanese straightening uses a strong relaxer to make hair pin-straight. A glyoxylic acid-based treatment like QIQI Hair Controller also works on the hair’s bonds, but more gently — it removes frizz, curl and volume without the harshness. And a temporary treatment like Nanokeratin simply washes out. Here is how to choose.
By Yasmin, founder of Nero Hair · Updated 22 September 2026
The short answer
It comes down to how straight — and how harsh.
Japanese straightening (also called thermal reconditioning) uses a strong chemical relaxer to break the bonds that give hair its shape, then irons it pin-straight. It is the most dramatic result, and the hardest on hair — many stylists will not do it on bleached or heavily coloured hair.
QIQI Hair Controller works on the same bonds but with a milder, glyoxylic acid-based, formaldehyde-free formula. It permanently reduces frizz, curl and volume on the hair you treat, with formulas for thick, curly and fine or coloured hair. New growth comes in at your natural texture, and you only treat the regrowth next time.
Nanokeratin System is different again: a temporary smoothing treatment that washes out over 12–16 weeks, with no regrowth line. It suits anyone who does not want a long-term change.
Straightest
Japanese
Gentlest long-term
QIQI Hair Controller
No regrowth line
Nanokeratin
At home?
QIQI & Nanokeratin
Side by side
How they compare.
| Japanese straightening | QIQI Hair Controller | Nanokeratin System | |
|---|---|---|---|
| How it works | Strong relaxer breaks and resets the hair’s bonds | Glyoxylic acid-based formula softens the bonds under heat | Temporary smoothing sealed with heat |
| Result | Pin-straight | Frizz, curl and volume reduced — sleek or softly textured by formula | Smooth, frizz-free |
| How long it lasts | Permanent on treated hair | Up to 5 months; treated hair stays smoother, regrowth is natural | 12–16 weeks, washes out |
| Regrowth | Clear line between straight and natural hair | New growth is natural texture — treat regrowth only | No regrowth line |
| Coloured / bleached hair | Often refused | Yes — Thin & Delicate formula | Yes — Refine and Replenish formulas |
| Formaldehyde | Not the main concern — the relaxer is | Formaldehyde-free | Formaldehyde-free |
| Where | Salon only, usually 3–6 hours | At home, 2–3 hours | At home or salon |
Japanese straightening
Who Japanese straightening suits.
It suits people with strong, healthy, uncoloured hair who want it as straight as possible and are happy to book root touch-ups. The result needs almost no styling.
The trade-offs are real. It is the harshest of the three, it is not usually offered on bleached hair, and it cannot be undone — if you want your natural texture back, you have to grow the straightened hair out. It must never be layered over hair that has already been chemically straightened.
QIQI Hair Controller
Who QIQI Hair Controller suits.
QIQI suits people who want a long-lasting change to their texture — less frizz, less curl, less volume — without a harsh relaxer. Because there are three formulas, you can match it to your hair: Thick & Coarse, Wavy & Curly, or Thin & Delicate for fine and colour-treated hair.
It is formaldehyde-free and designed to be applied at home in 2–3 hours. Like Japanese straightening, treated hair stays changed and new growth comes through at your natural texture — so on reapplication you only treat the regrowth, not the full length.
Nanokeratin System
Who a temporary treatment suits.
If you want smooth, frizz-free hair but do not want to change your hair long-term, a temporary treatment is the safest choice. Nanokeratin System lasts 12–16 weeks and washes out gradually, so there is no regrowth line and nothing to grow out.
It comes in specialist formulas — including Refortify for afro and textured hair, Refine for colour-treated hair and Replenish for blonde and bleached hair.
Switching between them
Can you go from one to another?
Tell whoever treats your hair your full history
Any bond-changing treatment — Japanese straightening or QIQI Hair Controller — affects what can safely go on next. A strand test first is always sensible.
Never layer relaxers
Japanese straightening should not go over hair that has already been chemically straightened. That is how breakage happens.
Temporary treatments are the flexible option
If you are unsure, start with a temporary treatment like Nanokeratin. It washes out, so you can decide what you want next.
What we recommend
Long-lasting or temporary — both at home.
QIQI Hair Controller for a long-lasting, formaldehyde-free change to your texture. Nanokeratin System if you would rather it washed out.
From £129 · 150g
Hair Controller — Thick & Coarse
Formaldehyde-free permanent smoothing treatment for thick, coarse, and afro-textured hair. Softens disulfide bonds under heat for lasting frizz control — from defined curls to fully straight. QIQI Hair Controller results last up to 5 months.
Shop now →
From £129 · 150g
Hair Controller — Wavy & Curly
Permanently reduces frizz and enhances natural pattern definition — or delivers a smooth, controlled finish. Designed specifically for wavy and curly hair. Formaldehyde-free. Lasts up to 5 months.
Shop now →
From £279 · 320ml / 1L
Revive Smoother — Natural Hair
Enzyme-based smoothing treatment for natural, straight, wavy, and unprocessed hair. Zero formaldehyde or aldehyde. Promotes bond reformation for frizz-free, manageable results lasting 12–16 weeks. Leaves hair smooth, shiny, and easy to style.
Shop now →Common questions
Japanese straightening vs keratin — FAQ
Which is better: Japanese straightening or keratin?
Japanese straightening is the choice if you want pin-straight hair and have strong, uncoloured hair. For most people, a gentler option is better: a glyoxylic acid-based treatment like QIQI Hair Controller for a long-lasting reduction in frizz and curl, or a temporary treatment like Nanokeratin that washes out in 12–16 weeks.
Is Japanese straightening more damaging than keratin?
Generally, yes. Japanese straightening uses a strong chemical relaxer and is often refused on bleached or heavily coloured hair. Glyoxylic acid-based treatments like QIQI are milder and have a formula for colour-treated hair, and temporary treatments like Nanokeratin do not permanently change the hair.
Is QIQI Hair Controller the same as Japanese straightening?
No. Both work on the hair’s bonds, so treated hair stays changed and new growth comes in natural. But QIQI uses a milder, glyoxylic acid-based, formaldehyde-free formula, comes in formulas for different hair types, and is designed for home use. Japanese straightening uses a stronger relaxer for a pin-straight result and is a salon-only service.
Does keratin grow out or wash out?
It depends on the treatment. QIQI Hair Controller changes the hair you treat, so new growth comes in at your natural texture and you treat the regrowth next time. Nanokeratin System is temporary and washes out gradually over 12–16 weeks, with no regrowth line.
Can you do Japanese straightening at home?
It is not recommended. It involves a strong relaxer that needs professional timing and application. QIQI Hair Controller and Nanokeratin System are designed to be applied at home.
Free UK delivery over £80
Smooth hair, without the relaxer.
Formaldehyde-free professional treatments and sulphate-free aftercare. Dispatched next working day. UK delivery 1–3 working days.